zlib.c

   1 /*
   2  * zlib wrappers to make sure we don't silently miss errors
   3  * at init time.
   4  */
   5 #include "cache.h"
   6
   7 static const char *zerr_to_string(int status)
   8 {
   9         switch (status) {
  10         case Z_MEM_ERROR:
  11                 return "out of memory";
  12         case Z_VERSION_ERROR:
  13                 return "wrong version";
  14         case Z_NEED_DICT:
  15                 return "needs dictionary";
  16         case Z_DATA_ERROR:
  17                 return "data stream error";
  18         case Z_STREAM_ERROR:
  19                 return "stream consistency error";
  20         default:
  21                 return "unknown error";
  22         }
  23 }
  24
  25 /*
  26  * avail_in and avail_out in zlib are counted in uInt, which typically
  27  * limits the size of the buffer we can use to 4GB when interacting
  28  * with zlib in a single call to inflate/deflate.
  29  */
  30 /* #define ZLIB_BUF_MAX ((uInt)-1) */
  31 #define ZLIB_BUF_MAX ((uInt) 1024 * 1024 * 1024) /* 1GB */
  32 static inline uInt zlib_buf_cap(unsigned long len)
  33 {
  34         return (ZLIB_BUF_MAX < len) ? ZLIB_BUF_MAX : len;
  35 }
  36
  37 static void zlib_pre_call(git_zstream *s)
  38 {
  39         s->z.next_in = s->next_in;
  40         s->z.next_out = s->next_out;
  41         s->z.total_in = s->total_in;
  42         s->z.total_out = s->total_out;
  43         s->z.avail_in = zlib_buf_cap(s->avail_in);
  44         s->z.avail_out = zlib_buf_cap(s->avail_out);
  45 }
  46
  47 static void zlib_post_call(git_zstream *s)
  48 {
  49         unsigned long bytes_consumed;
  50         unsigned long bytes_produced;
  51
  52         bytes_consumed = s->z.next_in - s->next_in;
  53         bytes_produced = s->z.next_out - s->next_out;
  54         if (s->z.total_out != s->total_out + bytes_produced)
  55                 die("BUG: total_out mismatch");
  56         if (s->z.total_in != s->total_in + bytes_consumed)
  57                 die("BUG: total_in mismatch");
  58
  59         s->total_out = s->z.total_out;
  60         s->total_in = s->z.total_in;
  61         s->next_in = s->z.next_in;
  62         s->next_out = s->z.next_out;
  63         s->avail_in -= bytes_consumed;
  64         s->avail_out -= bytes_produced;
  65 }
  66
  67 void git_inflate_init(git_zstream *strm)
  68 {
  69         int status;
  70
  71         zlib_pre_call(strm);
  72         status = inflateInit(&strm->z);
  73         zlib_post_call(strm);
  74         if (status == Z_OK)
  75                 return;
  76         die("inflateInit: %s (%s)", zerr_to_string(status),
  77             strm->z.msg ? strm->z.msg : "no message");
  78 }
  79
  80 void git_inflate_init_gzip_only(git_zstream *strm)
  81 {
  82         /*
  83          * Use default 15 bits, +16 is to accept only gzip and to
  84          * yield Z_DATA_ERROR when fed zlib format.
  85          */
  86         const int windowBits = 15 + 16;
  87         int status;
  88
  89         zlib_pre_call(strm);
  90         status = inflateInit2(&strm->z, windowBits);
  91         zlib_post_call(strm);
  92         if (status == Z_OK)
  93                 return;
  94         die("inflateInit2: %s (%s)", zerr_to_string(status),
  95             strm->z.msg ? strm->z.msg : "no message");
  96 }
  97
  98 void git_inflate_end(git_zstream *strm)
  99 {
 100         int status;
 101
 102         zlib_pre_call(strm);
 103         status = inflateEnd(&strm->z);
 104         zlib_post_call(strm);
 105         if (status == Z_OK)
 106                 return;
 107         error("inflateEnd: %s (%s)", zerr_to_string(status),
 108               strm->z.msg ? strm->z.msg : "no message");
 109 }
 110
 111 int git_inflate(git_zstream *strm, int flush)
 112 {
 113         int status;
 114
 115         for (;;) {
 116                 zlib_pre_call(strm);
 117                 /* Never say Z_FINISH unless we are feeding everything */
 118                 status = inflate(&strm->z,
 119                                  (strm->z.avail_in != strm->avail_in)
 120                                  ? 0 : flush);
 121                 if (status == Z_MEM_ERROR)
 122                         die("inflate: out of memory");
 123                 zlib_post_call(strm);
 124
 125                 /*
 126                  * Let zlib work another round, while we can still
 127                  * make progress.
 128                  */
 129                 if ((strm->avail_out && !strm->z.avail_out) &&
 130                     (status == Z_OK || status == Z_BUF_ERROR))
 131                         continue;
 132                 break;
 133         }
 134
 135         switch (status) {
 136         /* Z_BUF_ERROR: normal, needs more space in the output buffer */
 137         case Z_BUF_ERROR:
 138         case Z_OK:
 139         case Z_STREAM_END:
 140                 return status;
 141         default:
 142                 break;
 143         }
 144         error("inflate: %s (%s)", zerr_to_string(status),
 145               strm->z.msg ? strm->z.msg : "no message");
 146         return status;
 147 }
 148
 149 #if defined(NO_DEFLATE_BOUND) || ZLIB_VERNUM < 0x1200
 150 #define deflateBound(c,s)  ((s) + (((s) + 7) >> 3) + (((s) + 63) >> 6) + 11)
 151 #endif
 152
 153 unsigned long git_deflate_bound(git_zstream *strm, unsigned long size)
 154 {
 155         return deflateBound(&strm->z, size);
 156 }
 157
 158 void git_deflate_init(git_zstream *strm, int level)
 159 {
 160         int status;
 161
 162         zlib_pre_call(strm);
 163         status = deflateInit(&strm->z, level);
 164         zlib_post_call(strm);
 165         if (status == Z_OK)
 166                 return;
 167         die("deflateInit: %s (%s)", zerr_to_string(status),
 168             strm->z.msg ? strm->z.msg : "no message");
 169 }
 170
 171 static void do_git_deflate_init(git_zstream *strm, int level, int windowBits)
 172 {
 173         int status;
 174
 175         zlib_pre_call(strm);
 176         status = deflateInit2(&strm->z, level,
 177                                   Z_DEFLATED, windowBits,
 178                                   8, Z_DEFAULT_STRATEGY);
 179         zlib_post_call(strm);
 180         if (status == Z_OK)
 181                 return;
 182         die("deflateInit2: %s (%s)", zerr_to_string(status),
 183             strm->z.msg ? strm->z.msg : "no message");
 184 }
 185
 186 void git_deflate_init_gzip(git_zstream *strm, int level)
 187 {
 188         /*
 189          * Use default 15 bits, +16 is to generate gzip header/trailer
 190          * instead of the zlib wrapper.
 191          */
 192         do_git_deflate_init(strm, level, 15 + 16);
 193 }
 194
 195 void git_deflate_init_raw(git_zstream *strm, int level)
 196 {
 197         /*
 198          * Use default 15 bits, negate the value to get raw compressed
 199          * data without zlib header and trailer.
 200          */
 201         do_git_deflate_init(strm, level, -15);
 202 }
 203
 204 int git_deflate_abort(git_zstream *strm)
 205 {
 206         int status;
 207
 208         zlib_pre_call(strm);
 209         status = deflateEnd(&strm->z);
 210         zlib_post_call(strm);
 211         return status;
 212 }
 213
 214 void git_deflate_end(git_zstream *strm)
 215 {
 216         int status = git_deflate_abort(strm);
 217
 218         if (status == Z_OK)
 219                 return;
 220         error("deflateEnd: %s (%s)", zerr_to_string(status),
 221               strm->z.msg ? strm->z.msg : "no message");
 222 }
 223
 224 int git_deflate_end_gently(git_zstream *strm)
 225 {
 226         int status;
 227
 228         zlib_pre_call(strm);
 229         status = deflateEnd(&strm->z);
 230         zlib_post_call(strm);
 231         return status;
 232 }
 233
 234 int git_deflate(git_zstream *strm, int flush)
 235 {
 236         int status;
 237
 238         for (;;) {
 239                 zlib_pre_call(strm);
 240
 241                 /* Never say Z_FINISH unless we are feeding everything */
 242                 status = deflate(&strm->z,
 243                                  (strm->z.avail_in != strm->avail_in)
 244                                  ? 0 : flush);
 245                 if (status == Z_MEM_ERROR)
 246                         die("deflate: out of memory");
 247                 zlib_post_call(strm);
 248
 249                 /*
 250                  * Let zlib work another round, while we can still
 251                  * make progress.
 252                  */
 253                 if ((strm->avail_out && !strm->z.avail_out) &&
 254                     (status == Z_OK || status == Z_BUF_ERROR))
 255                         continue;
 256                 break;
 257         }
 258
 259         switch (status) {
 260         /* Z_BUF_ERROR: normal, needs more space in the output buffer */
 261         case Z_BUF_ERROR:
 262         case Z_OK:
 263         case Z_STREAM_END:
 264                 return status;
 265         default:
 266                 break;
 267         }
 268         error("deflate: %s (%s)", zerr_to_string(status),
 269               strm->z.msg ? strm->z.msg : "no message");
 270         return status;
 271 }